The invention relates generally to the field of small particle formation and more specifically to improvement of foods by the introduction of particles which are very small and uniform in size.
Advances in food technology are improving the foods that are available to consumers and promoting good health both through basic nutrition and through enhanced benefits of food products. Foods are being improved through the reduction or removal of certain components in a food, increasing the amount of certain components normally found in the food, or adding components to a food which are not normally found in the food. Products in which the amount of a component or ingredient naturally or normally present is increased or reduced include breakfast cereals with added bran or dairy products with reduced fat. Products with components or ingredients not normally present to any significant extent include fruit juice with added fiber, bread with added folic acid, and margarine spreads containing fish oils or olive oil.
Foods with components not normally present in those foods has become increasingly popular with the introduction of xe2x80x9cfunctional foodsxe2x80x9d. A functional food is any non-toxic food or food ingredient that has been altered to provide medical or health benefits, including the prevention and treatment of disease. Functional foods are similar in appearance to conventional foods that are consumed as part of a xe2x80x9cnormalxe2x80x9d diet, but have additives that demonstrate physiological benefits beyond their nutritive content. These products include genetically engineered xe2x80x9cdesignerxe2x80x9d foods, herbal products, and processed products, such as cereals, soups and beverages. Functional food product development reflects a major shift in attitude and an application of current knowledge about diet and health from xe2x80x98removing the badxe2x80x99 (for example, fat, cholesterol and salt) to xe2x80x98adding or enhancing the goodxe2x80x99 (such as calcium, fiber, antioxidants and botanicals). This has, in turn, paralleled consumer interest in healthy eating. Hollingsworth, P., Food Technol., 1997, 51, 55-8; Giese, J., and Katz, F., Food Technol., 1997, 51, 58-61. Consumers and their demand for an improved quality of life are bringing worldwide growth to the functional food industry.
Currently, a number of functional foods are being offered to consumers, including fortified breads, cereals, juices, and the like. For example, juice containing the patented calcium source FruitCal(trademark) (calcium citrate malate), U.S. Pat. No. 4,722,8470, which is more readily absorbable in juice ( greater than 35%) than calcium from milk or calcium carbonate supplements, is widely marketed. These fortified juices provide protection against osteoporosis and promote healthy teeth and bones. Certain functional foods are also being introduced to prevent, treat or ameliorate physiological conditions such as cardiovascular disease, hypercholesterolemia, and even menopause. For example, breakfast cereals with the compound PHYTROL(trademark) added are marketed as foods to control cholesterol.
The opportunity for future growth and development of new functional foods worldwide is tremendous. Overwhelming evidence supports the link between diet and optimal health, particularly the prevention of degenerative diseases of aging such as cancer, heart disease, osteoporosis, diabetes, arthritis and stroke. Given the extended life expectancy for those in developed nations and the commensurate increase in healthcare costs associated with treating chronic ageing diseases, there will be more of an emphasis in the future on a preventative rather than a prophylactic approach to healthcare. Diet will play a critical role in this new paradigm.
There is thus a new demand for new methods of improving foods by adding components to these foods to improve nutrient content, reduce the amount or percentage of unwanted components (e.g., fats) or provide functional components that increase the physiological response beyond that of conventional food products.
The invention is directed to production of particles for introduction into food using a stable microjet and a monodisperse aerosol of liquid particles formed when the microjet dissociates. A variety of devices and methods are disclosed which allow for the formation of a stream of a first fluid (e.g. a liquid) characterized by forming a stable capillary microjet over a portion of the stream wherein the microjet portion of the stream is formed by a second fluid (e.g. a gas). The second fluid is preferably in a different state from the first fluidxe2x80x94liquid-gas or gas-liquid combinations. However, the first and second fluids may be two different fluids immiscible in each other.
In preferred embodiments the first fluid is a liquid which forms a food or food additive and the second fluid is a gas which is non-toxic, e.g. air or nitrogen. In a particularly preferred embodiment the first fluid comprised of material which it would be desirable to have in but which can not be added to food for some reason, e.g. bad taste or reacts with the food. The first fluid is surrounded by a second fluid which is also a liquid, but which can coat and encapsulate the first fluid. A third fluid surrounds the second fluid and the third fluid is preferably a gas which focuses the liquid stream to a microjet. The jet will break up into particles where the first fluid (liquid food) is coated with the second fluid (liquid carrier coating). The coating provided by the second fluid keeps the bad taste or reactive effects of the first fluid from having its undesirable effects.
Many preferred embodiments provide a spheric food particle coated with a layer of another material which is non-toxic (e.g. a polymer which is degraded in the G.I.) and may or may not be a food product. The coating material may be a polymer which is maintained in a flowable liquid form until it coats the internal food particle after which the polymer coating is xe2x80x9ccured,xe2x80x9d polymerized or made non-flowable in some manner, e.g. by exposure to certain light energy, curing agent or a decreased temperature.
Although many specific embodiments described here relate specifically to foods those embodiments are applicable to drugs and nutriceuticals and other materials. Further, the drug embodiments described are applicable to foods, nutriceuticals and other materials.
The stable capillary microjet comprises a diameter dj at a given point A in the stream characterized by the formula:       d    j    ≅                    (                              8            ⁢                          xe2x80x83                        ⁢                          ρ              l                                                          π              2                        ⁢            Δ            ⁢                          xe2x80x83                        ⁢                          P              g                                      )                    1        /        4              ⁢          Q              1        /        2            
wherein dj is the diameter of the stable microjet, ≅ indicates approximately equally to where an acceptable margin of error is xc2x110%, xcfx811 is the density of the liquid and xcex94Pg is change in gas pressure of gas surrounding the stream at the point A, sunrrounding the stream from the feeding point to the point A, and wherein Q is the flow rate of the focused liquid.
The microjet can have a diameter in the range of from about 1 micron to about 1 mm and a length in the range of from 1 micron to 50 mm. The stable jet is maintained, at least in part, by tangential viscous stresses exerted by the gas on the surface of the jet in an axial direction of the jet. The jet is further characterized by a slightly parabolic axial velocity profile and still further characterized by a Weber number (We) which is greater than 1 with the Weber number being defined by the formula:   We  =                    ρ        g            ⁢              V        g        2            ⁢      d        γ  
wherein the xcfx81g is the density of the gas, d is the diameter of the stable microjet, xcex3 is the liquid-gas surface tension, and Vg2 is the velocity of the gas squared.
Although the Weber number is greater than 1 when a stable microjet is obtained the Weber number should be less than 40 to obtain a desired monodisperse aerosol. Thus, desired results are obtained within the parameters of 1xe2x89xa6Wexe2x89xa640. Monodisperse aerosols of the invention have a high degree of uniformity in particle size. The particles are characterized by having the same diameter with a deviation in diameter from one particle to another in a range of about xc2x12% or less to about xc2x130%, preferably about xc2x13% or less to about xc2x110% and most preferably xc2x13% or less. The particles in an aerosol will have consistency in size but may be produced to have a size in a range of about 0.1 micron to about 100 microns.
An object of the invention is to provide a stream of a first fluid (e.g. a liquid) which stream is characterized by forming a stable capillary microjet over a portion of the stream wherein this stable capillary microjet portion of the stream is formed by a second fluid (e.g. a gas) moving at a velocity greater than that of the first fluid.
Another object of the invention is to provide a monodisperse aerosol of liquid particles in air wherein the particles are characterized by having the same diameter with a deviation in diameter from one particle to another in a range of from about xc2x13% to about xc2x130% wherein the particles are produced as a result of a break up of the stable capillary microjet. These particles may be dessicated following dispersion, and then added to food, or may be added to the foods in liquid form.
An advantage of the invention is that the microjet of liquid flows through an opening surrounded by a focusing funnel of gas so that liquid does not touch the peripheral area of the opening and therefor does not deposit on the opening and cause clogging.
Another advantage of the invention is that the particles formed are highly uniform in size and are created with a relatively small amount of energy.
A feature of the invention is that various parameters including the viscosities and velocities of the fluids can be chosen with consideration to other adjusted parameters to obtain a supercritical flow of liquid which results in the formation of the stable microjet.
Another feature of the invention is the production of micronutrients, which are nutrients produced in a precise size range to increase the absorption and release of these nutrients in the bloodstream.
Another feature of the invention is the ability to coat particles or form hollow spheres, thus maintaining the surface area of a substance while decreasing the overall amount of the substance (e.g., a fiber particle coated with oil or a hollow sphere composed on an antimicrobial). This can also allow introduction of components that are generally incompatible with a food, such as introduction of lactase in milk, by coating the component.
Yet another feature of the invention is the use production of time-release components that will allow controlled delivery of the contents of the particle, e.g., carbohydrates particles coated to allow a systematic release over a twelve hour period.
These and other aspects, objects, features and advantages will become apparent to those skilled in the art upon reading this disclosure in combination with the figures provided.